The field of the invention is magnetic resonance spectroscopy. More particularly, the invention relates to a system and method for displaying magnetic resonance spectroscopy data that facilitates the review and analysis of the spectroscopy data.
Magnetic resonance spectroscopy (MRS) uses the nuclear magnetic resonance (NMR) phenomenon to produce spectra of tissue components. When a substance such as human tissue is subjected to a uniform magnetic field (polarizing field B0), the individual magnetic moments of the spins in the tissue attempt to align with this polarizing field, but precess about it in random order at their characteristic Larmor frequency. If the substance, or tissue, is subjected to a magnetic field (excitation field B1) that is in the x-y plane and that is near the Larmor frequency, the net aligned moment, Mz, may be rotated, or “tipped,” into the x-y plane to produce a net transverse magnetic moment Mt. A signal is emitted by the excited spins, and after the excitation signal B1 is terminated, this signal may be received and processed to form a spectrum of a particular substance.
Magnetic Resonance Spectroscopy (MRS) may be used in vivo for the determination of individual chemical compounds located within a volume of interest. The underlying principle of MRS is that atomic nuclei are surrounded by a cloud of electrons that slightly shield the nucleus from any external magnetic field. As the structure of the electron cloud is specific to an individual molecule or compound, the magnitude of this screening effect is then also a characteristic of the chemical environment of individual nuclei. Since the resonant frequency of the nuclei is proportional to the magnetic field it experiences, the resonant frequency can be determined not only by the external applied field, but also by the small field shift generated by the electron cloud. Detection of this chemical shift, which is usually expressed as “parts per million” (PPM) of the main frequency, requires high levels of homogeneity of the main magnetic field B0.
Typically, MR proton spectroscopy is used to generate a one-dimensional (1D) frequency spectrum representing the presence of certain chemical bonds in the region of interest. In medical diagnosis and treatment, MRS provides a non-invasive means of identifying and quantifying metabolites from a region of interest, often the human brain. For example, some metabolites of particular interest in proton MRS studies include glutamate/glutainine (Glx), choline (Cho), phosphocreatine ((P)Cr), N-acetylaspartate (NAA), and the inositols (mI and sI). By finding the relative spectral amplitudes resulting from frequency components of different molecules, medical professionals can identify chemical species and metabolites indicative of diseases, disorders, and other pathologies such as Alzheimer's disease, cancer, stroke, and the like.
For example, FIG. 1 shows a traditional 1D frequency spectrum line graph generated using MR spectroscopy. The data acquired using MRS spectroscopy is typically represented as a continuous spectrum that shows the relative spectral amplitudes of each chemical species and metabolite.
While traditional spectral graphs generally allow a radiologist or physician to compare relative spectral amplitudes in a 1D-frequency spectrum, the task of comparing the relative amplitudes becomes more difficult when performing two-dimensional (2D) spectroscopy. In this case, the radiologist or physician must analyze multiple spectra, such as illustrated in FIG. 2, to discern subtle variations in the relative amplitude within each spectrum and between adjacent and non-adjacent spectra.
Therefore, it would be desirable to have a system and method for facilitating the review and analysis of data acquired with MR spectroscopy.